From 770292a42cf28440a01dfa2c21f16130b4a383c2 Mon Sep 17 00:00:00 2001
From: ntoniazzi <ntoniazzi@poste-062>
Date: Tue, 11 Dec 2012 11:49:30 +0100
Subject: [PATCH 1/9] Conforming to XDG Base Directory Specification
 (http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html)

---
 src/Composer/Factory.php | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index d02f68d41..c2565c0b4 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -42,7 +42,11 @@ class Factory
             if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
                 $home = getenv('APPDATA') . '/Composer';
             } else {
-                $home = rtrim(getenv('HOME'), '/') . '/.composer';
+                $xdgConfig = getenv('XDG_CONFIG_HOME');
+                if (!$xdgConfig) {
+                    $xdgConfig = rtrim(getenv('HOME'), '/') . '/.config';
+                }
+                $home = $xdgConfig . '/composer';
             }
         }
         if (!$cacheDir) {
@@ -53,7 +57,11 @@ class Factory
                     $cacheDir = getenv('APPDATA') . '/Composer/cache';
                 }
             } else {
-                $cacheDir = $home.'/cache';
+                $xdgCache = getenv('XDG_CACHE_HOME');
+                if (!$xdgCache) {
+                    $xdgCache = rtrim(getenv('HOME'), '/') . '/.cache';
+                }
+                $cacheDir = $xdgCache . '/composer';
             }
         }
 

From 6821e3efcc49a813b76f59bce6a625b14d88ab13 Mon Sep 17 00:00:00 2001
From: ntoniazzi <ntoniazzi@poste-062>
Date: Wed, 2 Jan 2013 13:48:00 +0100
Subject: [PATCH 2/9] Conforming to XDG Base Directory Specification
 (http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html)

---
 doc/03-cli.md            |  8 +++++---
 doc/04-schema.md         |  5 +++--
 src/Composer/Factory.php | 34 +++++++++++++++++++++++++++++-----
 3 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/doc/03-cli.md b/doc/03-cli.md
index 870509c3a..7bec79bba 100644
--- a/doc/03-cli.md
+++ b/doc/03-cli.md
@@ -400,9 +400,11 @@ The `COMPOSER_HOME` var allows you to change the composer home directory. This
 is a hidden, global (per-user on the machine) directory that is shared between
 all projects.
 
-By default it points to `/home/<user>/.composer` on *nix,
-`/Users/<user>/.composer` on OSX and
-`C:\Users\<user>\AppData\Roaming\Composer` on Windows.
+By default it points to `C:\Users\<user>\AppData\Roaming\Composer` on Windows
+and `/Users/<user>/.composer` on OSX. On *nix systems that follow the [XDG Base
+Directory Specifications](http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html),
+it points to `$XDG_CONFIG_HOME/composer`. On other *nix systems, it points to
+`/home/<user>/.composer`.
 
 #### COMPOSER_HOME/config.json
 
diff --git a/doc/04-schema.md b/doc/04-schema.md
index 71c4fd692..0f7096f12 100644
--- a/doc/04-schema.md
+++ b/doc/04-schema.md
@@ -598,8 +598,9 @@ The following options are supported:
   `{"github.com": "oauthtoken"}` as the value of this option will use `oauthtoken`
   to access private repositories on github and to circumvent the low IP-based
   rate limiting of their API.
-* **cache-dir:** Defaults to `$home/cache` on unix systems and
-  `C:\Users\<user>\AppData\Local\Composer` on Windows. Stores all the caches
+* **cache-dir:** Defaults to `C:\Users\<user>\AppData\Local\Composer` on Windows,
+  `$XDG_CACHE_HOME/composer` on unix systems that follow the XDG Base Directory
+  Specifications, and `$home/cache` on other unix systems. Stores all the caches
   used by composer. See also [COMPOSER_HOME](03-cli.md#composer-home).
 * **cache-files-dir:** Defaults to `$cache-dir/files`. Stores the zip archives
   of packages.
diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index c2565c0b4..2dbf52dfa 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -38,15 +38,21 @@ class Factory
         // determine home and cache dirs
         $home = getenv('COMPOSER_HOME');
         $cacheDir = getenv('COMPOSER_CACHE_DIR');
+        $userDir = rtrim(getenv('HOME'), '/');
+        $followXDG = false;
         if (!$home) {
             if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
                 $home = getenv('APPDATA') . '/Composer';
-            } else {
+            } elseif (getenv('XDG_CONFIG_DIRS')) {
+                // XDG Base Directory Specifications
+                $followXDG = true;
                 $xdgConfig = getenv('XDG_CONFIG_HOME');
                 if (!$xdgConfig) {
-                    $xdgConfig = rtrim(getenv('HOME'), '/') . '/.config';
+                    $xdgConfig = $userDir . '/.config';
                 }
                 $home = $xdgConfig . '/composer';
+            } else {
+                $home = $userDir . '/.composer';
             }
         }
         if (!$cacheDir) {
@@ -56,15 +62,20 @@ class Factory
                 } else {
                     $cacheDir = getenv('APPDATA') . '/Composer/cache';
                 }
-            } else {
+            } elseif (getenv('XDG_CONFIG_DIRS')) {
+                $followXDG = true;
                 $xdgCache = getenv('XDG_CACHE_HOME');
                 if (!$xdgCache) {
-                    $xdgCache = rtrim(getenv('HOME'), '/') . '/.cache';
+                    $xdgCache = $userDir . '/.cache';
                 }
                 $cacheDir = $xdgCache . '/composer';
+
+
+            } else {
+                $cacheDir = $home . '/.cache';
             }
         }
-
+        
         // Protect directory against web access. Since HOME could be
         // the www-data's user home and be web-accessible it is a
         // potential security risk
@@ -77,6 +88,19 @@ class Factory
             }
         }
 
+        // Move content of old composer dir to XDG
+        if ($followXDG && file_exists($userDir . '/.composer')) {
+            // migrate to XDG
+            @rename($userDir . '/.composer/config.json', $home . '/config.json');
+            @unlink($userDir . '/.composer/.htaccess');
+            @unlink($userDir . '/.composer/cache/.htaccess');
+            foreach (glob($userDir . '/.composer/cache/*') as $oldCacheDir) {
+                @rename($oldCacheDir, $cacheDir . '/' . basename($oldCacheDir));
+            }
+            @rmdir($userDir . '/.composer/cache');
+            @rmdir($userDir . '/.composer');
+        }
+
         $config = new Config();
 
         // add dirs to the config

From 50c6c100fa65a47f112197408d93169d0dba9b0f Mon Sep 17 00:00:00 2001
From: Nicolas Toniazzi <nicolas@toniazzi.net>
Date: Thu, 16 Oct 2014 14:39:48 +0200
Subject: [PATCH 3/9] Added support for backup PHARs

---
 src/Composer/Command/SelfUpdateCommand.php |   2 +-
 src/Composer/Config.php                    |   2 +
 src/Composer/Factory.php                   | 138 +++++++++++++--------
 3 files changed, 90 insertions(+), 52 deletions(-)

diff --git a/src/Composer/Command/SelfUpdateCommand.php b/src/Composer/Command/SelfUpdateCommand.php
index 13abee32b..2975a7fa0 100644
--- a/src/Composer/Command/SelfUpdateCommand.php
+++ b/src/Composer/Command/SelfUpdateCommand.php
@@ -61,7 +61,7 @@ EOT
         $config = Factory::createConfig();
         $remoteFilesystem = new RemoteFilesystem($this->getIO(), $config);
         $cacheDir = $config->get('cache-dir');
-        $rollbackDir = $config->get('home');
+        $rollbackDir = $config->get('data-dir');
         $localFilename = realpath($_SERVER['argv'][0]) ?: $_SERVER['argv'][0];
 
         // check if current dir is writable and if not try the cache dir from settings
diff --git a/src/Composer/Config.php b/src/Composer/Config.php
index d5b41efe2..478dad84a 100644
--- a/src/Composer/Config.php
+++ b/src/Composer/Config.php
@@ -28,6 +28,7 @@ class Config
         'vendor-dir' => 'vendor',
         'bin-dir' => '{$vendor-dir}/bin',
         'cache-dir' => '{$home}/cache',
+        'data-dir' => '{$home}',
         'cache-files-dir' => '{$cache-dir}/files',
         'cache-repo-dir' => '{$cache-dir}/repo',
         'cache-vcs-dir' => '{$cache-dir}/vcs',
@@ -151,6 +152,7 @@ class Config
             case 'vendor-dir':
             case 'bin-dir':
             case 'process-timeout':
+            case 'data-dir':
             case 'cache-dir':
             case 'cache-files-dir':
             case 'cache-repo-dir':
diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index 10a3c3cab..229c4653c 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -36,6 +36,7 @@ use Composer\Package\Version\VersionParser;
  */
 class Factory
 {
+
     /**
      * @return string
      * @throws \RuntimeException
@@ -43,29 +44,28 @@ class Factory
     protected static function getHomeDir()
     {
         $home = getenv('COMPOSER_HOME');
-        $cacheDir = getenv('COMPOSER_CACHE_DIR');
-        if (!getenv('HOME')) {
-            throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
-        }
-        $userDir = rtrim(getenv('HOME'), '/');
-        $followXDG = false;
-
         if (!$home) {
             if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
                 if (!getenv('APPDATA')) {
                     throw new \RuntimeException('The APPDATA or COMPOSER_HOME environment variable must be set for composer to run correctly');
                 }
-                $home = getenv('APPDATA') . '/Composer';
-            } elseif (getenv('XDG_CONFIG_DIRS')) {
-                // XDG Base Directory Specifications
-                $followXDG = true;
-                $xdgConfig = getenv('XDG_CONFIG_HOME');
-                if (!$xdgConfig) {
-                    $xdgConfig = $userDir . '/.config';
-                }
-                $home = $xdgConfig . '/composer';
+                $home = strtr(getenv('APPDATA'), '\\', '/') . '/Composer';
             } else {
-                $home = $userDir . '/.composer';
+                if (!getenv('HOME')) {
+                    throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
+                }
+                $userDir = rtrim(getenv('HOME'), '/');
+
+                if (getenv('XDG_CONFIG_DIRS')) {
+                    // XDG Base Directory Specifications
+                    $xdgConfig = getenv('XDG_CONFIG_HOME');
+                    if (!$xdgConfig) {
+                        $xdgConfig = $userDir . '/.config';
+                    }
+                    $home = $xdgConfig . '/composer';
+                } else {
+                    $home = $userDir . '/composer';
+                }
             }
         }
 
@@ -87,23 +87,47 @@ class Factory
                 } else {
                     $cacheDir = $home . '/cache';
                 }
-
                 $cacheDir = strtr($cacheDir, '\\', '/');
             } elseif (getenv('XDG_CONFIG_DIRS')) {
-                $followXDG = true;
                 $xdgCache = getenv('XDG_CACHE_HOME');
                 if (!$xdgCache) {
-                    $xdgCache = $userDir . '/.cache';
+                    $xdgCache = $home . '/.cache';
                 }
                 $cacheDir = $xdgCache . '/composer';
             } else {
-                $cacheDir = $home . '/.cache';
+                $cacheDir = $home . '/cache';
             }
         }
 
         return $cacheDir;
     }
 
+    /**
+     * @param string $home
+     *
+     * @return string
+     */
+    protected static function getDataDir($home)
+    {
+        if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
+            $dataDir = strtr($home, '\\', '/');
+        } elseif (getenv('XDG_CONFIG_DIRS')) {
+            $xdgData = getenv('XDG_DATA_HOME');
+            if (!$xdgData) {
+                if (!getenv('HOME')) {
+                    throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
+                }
+                $userDir = rtrim(getenv('HOME'), '/');
+                $xdgData = $userDir . '/.local/share';
+            }
+            $dataDir = $xdgData . '/composer';
+        } else {
+            $dataDir = $home;
+        }
+
+        return $dataDir;
+    }
+
     /**
      * @param IOInterface|null $io
      * @return Config
@@ -113,11 +137,12 @@ class Factory
         // determine home and cache dirs
         $home     = self::getHomeDir();
         $cacheDir = self::getCacheDir($home);
+        $dataDir  = self::getDataDir($home);
 
         // Protect directory against web access. Since HOME could be
         // the www-data's user home and be web-accessible it is a
         // potential security risk
-        foreach (array($home, $cacheDir) as $dir) {
+        foreach (array($home, $cacheDir, $dataDir) as $dir) {
             if (!file_exists($dir . '/.htaccess')) {
                 if (!is_dir($dir)) {
                     @mkdir($dir, 0777, true);
@@ -127,22 +152,34 @@ class Factory
         }
 
         // Move content of old composer dir to XDG
-        if ($followXDG && file_exists($userDir . '/.composer')) {
-            // migrate to XDG
-            @rename($userDir . '/.composer/config.json', $home . '/config.json');
-            @unlink($userDir . '/.composer/.htaccess');
-            @unlink($userDir . '/.composer/cache/.htaccess');
-            foreach (glob($userDir . '/.composer/cache/*') as $oldCacheDir) {
-                @rename($oldCacheDir, $cacheDir . '/' . basename($oldCacheDir));
+        if (getenv('XDG_CONFIG_DIRS') !== false && getenv('COMPOSER_HOME') === false && getenv('COMPOSER_CACHE_DIR') === false) {
+            $userDir         = rtrim(getenv('HOME'), '/');
+            $oldComposerHome = $userDir . '/.composer';
+            if (file_exists($oldComposerHome)) {
+                // migrate to XDG
+                foreach (glob($oldComposerHome . '/*.json') as $file) {
+                    rename($file, $home . '/' . basename($file));
+                }
+
+                foreach (glob($oldComposerHome . '/*.phar') as $file) {
+                    rename($file, $dataDir . '/' . basename($file));
+                }
+
+                foreach (glob($oldComposerHome . '/cache/*') as $oldCacheDir) {
+                    rename($oldCacheDir, $cacheDir . '/' . basename($oldCacheDir));
+                }
+
+                unlink($oldComposerHome . '/.htaccess');
+                unlink($oldComposerHome . '/cache/.htaccess');
+                rmdir($oldComposerHome . '/cache');
+                rmdir($oldComposerHome);
             }
-            @rmdir($userDir . '/.composer/cache');
-            @rmdir($userDir . '/.composer');
         }
 
         $config = new Config();
 
         // add dirs to the config
-        $config->merge(array('config' => array('home' => $home, 'cache-dir' => $cacheDir)));
+        $config->merge(array('config' => array('home' => $home, 'cache-dir' => $cacheDir, 'data-dir' => $dataDir)));
 
         // load global config
         $file = new JsonFile($home.'/config.json');
@@ -169,14 +206,14 @@ class Factory
 
     public static function getComposerFile()
     {
-        return trim(getenv('COMPOSER')) ?: './composer.json';
+        return trim(getenv('COMPOSER')) ? : './composer.json';
     }
 
     public static function createAdditionalStyles()
     {
         return array(
             'highlight' => new OutputFormatterStyle('red'),
-            'warning' => new OutputFormatterStyle('black', 'yellow'),
+            'warning'   => new OutputFormatterStyle('black', 'yellow'),
         );
     }
 
@@ -192,15 +229,15 @@ class Factory
                 throw new \InvalidArgumentException('This function requires either an IOInterface or a RepositoryManager');
             }
             $factory = new static;
-            $rm = $factory->createRepositoryManager($io, $config);
+            $rm      = $factory->createRepositoryManager($io, $config);
         }
 
         foreach ($config->getRepositories() as $index => $repo) {
             if (!is_array($repo)) {
-                throw new \UnexpectedValueException('Repository '.$index.' ('.json_encode($repo).') should be an array, '.gettype($repo).' given');
+                throw new \UnexpectedValueException('Repository ' . $index . ' (' . json_encode($repo) . ') should be an array, ' . gettype($repo) . ' given');
             }
             if (!isset($repo['type'])) {
-                throw new \UnexpectedValueException('Repository '.$index.' ('.json_encode($repo).') must have a type defined');
+                throw new \UnexpectedValueException('Repository ' . $index . ' (' . json_encode($repo) . ') must have a type defined');
             }
             $name = is_int($index) && isset($repo['url']) ? preg_replace('{^https?://}i', '', $repo['url']) : $index;
             while (isset($repos[$name])) {
@@ -232,16 +269,16 @@ class Factory
 
         if (is_string($localConfig)) {
             $composerFile = $localConfig;
-            $file = new JsonFile($localConfig, new RemoteFilesystem($io));
+            $file         = new JsonFile($localConfig, new RemoteFilesystem($io));
 
             if (!$file->exists()) {
                 if ($localConfig === './composer.json' || $localConfig === 'composer.json') {
-                    $message = 'Composer could not find a composer.json file in '.getcwd();
+                    $message = 'Composer could not find a composer.json file in ' . getcwd();
                 } else {
-                    $message = 'Composer could not find the config file: '.$localConfig;
+                    $message = 'Composer could not find the config file: ' . $localConfig;
                 }
                 $instructions = 'To initialize a project, please create a composer.json file as described in the http://getcomposer.org/ "Getting Started" section';
-                throw new \InvalidArgumentException($message.PHP_EOL.$instructions);
+                throw new \InvalidArgumentException($message . PHP_EOL . $instructions);
             }
 
             $file->validateSchema(JsonFile::LAX_SCHEMA);
@@ -269,7 +306,7 @@ class Factory
         $io->loadConfiguration($config);
 
         $vendorDir = $config->get('vendor-dir');
-        $binDir = $config->get('bin-dir');
+        $binDir    = $config->get('bin-dir');
 
         // setup process timeout
         ProcessExecutor::setTimeout((int) $config->get('process-timeout'));
@@ -288,7 +325,7 @@ class Factory
         $this->addLocalRepository($rm, $vendorDir);
 
         // load package
-        $parser = new VersionParser;
+        $parser  = new VersionParser;
         $loader  = new Package\Loader\RootPackageLoader($rm, $config, $parser, new ProcessExecutor($io));
         $package = $loader->load($localConfig);
 
@@ -314,7 +351,7 @@ class Factory
         $this->createDefaultInstallers($im, $composer, $io);
 
         $globalRepository = $this->createGlobalRepository($config, $vendorDir);
-        $pm = $this->createPluginManager($composer, $io, $globalRepository);
+        $pm               = $this->createPluginManager($composer, $io, $globalRepository);
         $composer->setPluginManager($pm);
 
         if (!$disablePlugins) {
@@ -326,10 +363,8 @@ class Factory
 
         // init locker if possible
         if (isset($composerFile)) {
-            $lockFile = "json" === pathinfo($composerFile, PATHINFO_EXTENSION)
-                ? substr($composerFile, 0, -4).'lock'
-                : $composerFile . '.lock';
-            $locker = new Package\Locker($io, new JsonFile($lockFile, new RemoteFilesystem($io, $config)), $rm, $im, md5_file($composerFile));
+            $lockFile = "json" === pathinfo($composerFile, PATHINFO_EXTENSION) ? substr($composerFile, 0, -4) . 'lock' : $composerFile . '.lock';
+            $locker   = new Package\Locker($io, new JsonFile($lockFile, new RemoteFilesystem($io, $config)), $rm, $im, md5_file($composerFile));
             $composer->setLocker($locker);
         }
 
@@ -364,10 +399,10 @@ class Factory
      */
     protected function addLocalRepository(RepositoryManager $rm, $vendorDir)
     {
-        $rm->setLocalRepository(new Repository\InstalledFilesystemRepository(new JsonFile($vendorDir.'/composer/installed.json')));
+        $rm->setLocalRepository(new Repository\InstalledFilesystemRepository(new JsonFile($vendorDir . '/composer/installed.json')));
     }
 
-     /**
+    /**
      * @param Config $config
      * @param string $vendorDir
      * @return Repository\InstalledFilesystemRepository|null
@@ -378,7 +413,7 @@ class Factory
             return null;
         }
 
-        $path = $config->get('home').'/vendor/composer/installed.json';
+        $path = $config->get('home') . '/vendor/composer/installed.json';
         if (!file_exists($path)) {
             return null;
         }
@@ -506,4 +541,5 @@ class Factory
 
         return $factory->createComposer($io, $config, $disablePlugins);
     }
+
 }

From c6860400f0814094cd4acf1c5b13d5f5868684d0 Mon Sep 17 00:00:00 2001
From: ntoniazzi <ntoniazzi@poste-062>
Date: Tue, 11 Dec 2012 11:49:30 +0100
Subject: [PATCH 4/9] Conforming to XDG Base Directory Specification
 (http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html)

---
 src/Composer/Factory.php | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index 4f7bfefd8..cc20cd575 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -50,10 +50,11 @@ class Factory
                 }
                 $home = strtr(getenv('APPDATA'), '\\', '/') . '/Composer';
             } else {
-                if (!getenv('HOME')) {
-                    throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
+                $xdgConfig = getenv('XDG_CONFIG_HOME');
+                if (!$xdgConfig) {
+                    $xdgConfig = rtrim(getenv('HOME'), '/') . '/.config';
                 }
-                $home = rtrim(getenv('HOME'), '/') . '/.composer';
+                $home = $xdgConfig . '/composer';
             }
         }
 
@@ -77,7 +78,11 @@ class Factory
                 }
                 $cacheDir = strtr($cacheDir, '\\', '/');
             } else {
-                $cacheDir = $home.'/cache';
+                $xdgCache = getenv('XDG_CACHE_HOME');
+                if (!$xdgCache) {
+                    $xdgCache = rtrim(getenv('HOME'), '/') . '/.cache';
+                }
+                $cacheDir = $xdgCache . '/composer';
             }
         }
 

From b79f38fd9949601ce53df8fbed646ca26d8dbee7 Mon Sep 17 00:00:00 2001
From: ntoniazzi <ntoniazzi@poste-062>
Date: Wed, 2 Jan 2013 13:48:00 +0100
Subject: [PATCH 5/9] Conforming to XDG Base Directory Specification
 (http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html)

---
 doc/03-cli.md            |  8 +++---
 doc/04-schema.md         | 15 +++--------
 src/Composer/Factory.php | 54 +++++++++++++++++++++++-----------------
 3 files changed, 39 insertions(+), 38 deletions(-)

diff --git a/doc/03-cli.md b/doc/03-cli.md
index 7fcafc2d6..dd708100c 100644
--- a/doc/03-cli.md
+++ b/doc/03-cli.md
@@ -598,9 +598,11 @@ The `COMPOSER_HOME` var allows you to change the composer home directory. This
 is a hidden, global (per-user on the machine) directory that is shared between
 all projects.
 
-By default it points to `/home/<user>/.composer` on \*nix,
-`/Users/<user>/.composer` on OSX and
-`C:\Users\<user>\AppData\Roaming\Composer` on Windows.
+By default it points to `C:\Users\<user>\AppData\Roaming\Composer` on Windows
+and `/Users/<user>/.composer` on OSX. On *nix systems that follow the [XDG Base
+Directory Specifications](http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html),
+it points to `$XDG_CONFIG_HOME/composer`. On other *nix systems, it points to
+`/home/<user>/.composer`.
 
 #### COMPOSER_HOME/config.json
 
diff --git a/doc/04-schema.md b/doc/04-schema.md
index c768edb72..3a40d5d93 100644
--- a/doc/04-schema.md
+++ b/doc/04-schema.md
@@ -754,18 +754,9 @@ The following options are supported:
   `{"github.com": "oauthtoken"}` as the value of this option will use `oauthtoken`
   to access private repositories on github and to circumvent the low IP-based
   rate limiting of their API.
-  [Read more](articles/troubleshooting.md#api-rate-limit-and-oauth-tokens)
-  on how to get an OAuth token for GitHub.
-* **http-basic:** A list of domain names and username/passwords to authenticate
-  against them. For example using
-  `{"example.org": {"username": "alice", "password": "foo"}` as the value of this option will let composer authenticate against example.org.
-* **vendor-dir:** Defaults to `vendor`. You can install dependencies into a
-  different directory if you want to. `$HOME` and `~` will be replaced by your
-  home directory's path in vendor-dir and all `*-dir` options below.
-* **bin-dir:** Defaults to `vendor/bin`. If a project includes binaries, they
-  will be symlinked into this directory.
-* **cache-dir:** Defaults to `$home/cache` on unix systems and
-  `C:\Users\<user>\AppData\Local\Composer` on Windows. Stores all the caches
+* **cache-dir:** Defaults to `C:\Users\<user>\AppData\Local\Composer` on Windows,
+  `$XDG_CACHE_HOME/composer` on unix systems that follow the XDG Base Directory
+  Specifications, and `$home/cache` on other unix systems. Stores all the caches
   used by composer. See also [COMPOSER_HOME](03-cli.md#composer-home).
 * **cache-files-dir:** Defaults to `$cache-dir/files`. Stores the zip archives
   of packages.
diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index cc20cd575..0dddab3df 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -43,18 +43,22 @@ class Factory
     protected static function getHomeDir()
     {
         $home = getenv('COMPOSER_HOME');
+        $cacheDir = getenv('COMPOSER_CACHE_DIR');
+        $userDir = rtrim(getenv('HOME'), '/');
+        $followXDG = false;
         if (!$home) {
             if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
-                if (!getenv('APPDATA')) {
-                    throw new \RuntimeException('The APPDATA or COMPOSER_HOME environment variable must be set for composer to run correctly');
-                }
-                $home = strtr(getenv('APPDATA'), '\\', '/') . '/Composer';
-            } else {
+                $home = getenv('APPDATA') . '/Composer';
+            } elseif (getenv('XDG_CONFIG_DIRS')) {
+                // XDG Base Directory Specifications
+                $followXDG = true;
                 $xdgConfig = getenv('XDG_CONFIG_HOME');
                 if (!$xdgConfig) {
-                    $xdgConfig = rtrim(getenv('HOME'), '/') . '/.config';
+                    $xdgConfig = $userDir . '/.config';
                 }
                 $home = $xdgConfig . '/composer';
+            } else {
+                $home = $userDir . '/.composer';
             }
         }
 
@@ -76,29 +80,20 @@ class Factory
                 } else {
                     $cacheDir = $home . '/cache';
                 }
-                $cacheDir = strtr($cacheDir, '\\', '/');
-            } else {
+            } elseif (getenv('XDG_CONFIG_DIRS')) {
+                $followXDG = true;
                 $xdgCache = getenv('XDG_CACHE_HOME');
                 if (!$xdgCache) {
-                    $xdgCache = rtrim(getenv('HOME'), '/') . '/.cache';
+                    $xdgCache = $userDir . '/.cache';
                 }
                 $cacheDir = $xdgCache . '/composer';
+
+
+            } else {
+                $cacheDir = $home . '/.cache';
             }
         }
-
-        return $cacheDir;
-    }
-
-    /**
-     * @param  IOInterface|null $io
-     * @return Config
-     */
-    public static function createConfig(IOInterface $io = null)
-    {
-        // determine home and cache dirs
-        $home     = self::getHomeDir();
-        $cacheDir = self::getCacheDir($home);
-
+        
         // Protect directory against web access. Since HOME could be
         // the www-data's user home and be web-accessible it is a
         // potential security risk
@@ -111,6 +106,19 @@ class Factory
             }
         }
 
+        // Move content of old composer dir to XDG
+        if ($followXDG && file_exists($userDir . '/.composer')) {
+            // migrate to XDG
+            @rename($userDir . '/.composer/config.json', $home . '/config.json');
+            @unlink($userDir . '/.composer/.htaccess');
+            @unlink($userDir . '/.composer/cache/.htaccess');
+            foreach (glob($userDir . '/.composer/cache/*') as $oldCacheDir) {
+                @rename($oldCacheDir, $cacheDir . '/' . basename($oldCacheDir));
+            }
+            @rmdir($userDir . '/.composer/cache');
+            @rmdir($userDir . '/.composer');
+        }
+
         $config = new Config();
 
         // add dirs to the config

From 83a144128527b5b74189b50d14124b56121599ca Mon Sep 17 00:00:00 2001
From: Nicolas Toniazzi <nicolas@toniazzi.net>
Date: Thu, 16 Oct 2014 14:39:48 +0200
Subject: [PATCH 6/9] Added support for backup PHARs

---
 src/Composer/Command/SelfUpdateCommand.php |   2 +-
 src/Composer/Config.php                    |   2 +
 src/Composer/Factory.php                   | 154 ++++++++++++++-------
 3 files changed, 109 insertions(+), 49 deletions(-)

diff --git a/src/Composer/Command/SelfUpdateCommand.php b/src/Composer/Command/SelfUpdateCommand.php
index 13abee32b..2975a7fa0 100644
--- a/src/Composer/Command/SelfUpdateCommand.php
+++ b/src/Composer/Command/SelfUpdateCommand.php
@@ -61,7 +61,7 @@ EOT
         $config = Factory::createConfig();
         $remoteFilesystem = new RemoteFilesystem($this->getIO(), $config);
         $cacheDir = $config->get('cache-dir');
-        $rollbackDir = $config->get('home');
+        $rollbackDir = $config->get('data-dir');
         $localFilename = realpath($_SERVER['argv'][0]) ?: $_SERVER['argv'][0];
 
         // check if current dir is writable and if not try the cache dir from settings
diff --git a/src/Composer/Config.php b/src/Composer/Config.php
index bd5d86895..b6ef01aa4 100644
--- a/src/Composer/Config.php
+++ b/src/Composer/Config.php
@@ -28,6 +28,7 @@ class Config
         'vendor-dir' => 'vendor',
         'bin-dir' => '{$vendor-dir}/bin',
         'cache-dir' => '{$home}/cache',
+        'data-dir' => '{$home}',
         'cache-files-dir' => '{$cache-dir}/files',
         'cache-repo-dir' => '{$cache-dir}/repo',
         'cache-vcs-dir' => '{$cache-dir}/vcs',
@@ -157,6 +158,7 @@ class Config
             case 'vendor-dir':
             case 'bin-dir':
             case 'process-timeout':
+            case 'data-dir':
             case 'cache-dir':
             case 'cache-files-dir':
             case 'cache-repo-dir':
diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index 0dddab3df..0c68adf5b 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -36,6 +36,7 @@ use Composer\Package\Version\VersionParser;
  */
 class Factory
 {
+
     /**
      * @return string
      * @throws \RuntimeException
@@ -43,22 +44,28 @@ class Factory
     protected static function getHomeDir()
     {
         $home = getenv('COMPOSER_HOME');
-        $cacheDir = getenv('COMPOSER_CACHE_DIR');
-        $userDir = rtrim(getenv('HOME'), '/');
-        $followXDG = false;
         if (!$home) {
             if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
-                $home = getenv('APPDATA') . '/Composer';
-            } elseif (getenv('XDG_CONFIG_DIRS')) {
-                // XDG Base Directory Specifications
-                $followXDG = true;
-                $xdgConfig = getenv('XDG_CONFIG_HOME');
-                if (!$xdgConfig) {
-                    $xdgConfig = $userDir . '/.config';
+                if (!getenv('APPDATA')) {
+                    throw new \RuntimeException('The APPDATA or COMPOSER_HOME environment variable must be set for composer to run correctly');
                 }
-                $home = $xdgConfig . '/composer';
+                $home = strtr(getenv('APPDATA'), '\\', '/') . '/Composer';
             } else {
-                $home = $userDir . '/.composer';
+                if (!getenv('HOME')) {
+                    throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
+                }
+                $userDir = rtrim(getenv('HOME'), '/');
+
+                if (getenv('XDG_CONFIG_DIRS')) {
+                    // XDG Base Directory Specifications
+                    $xdgConfig = getenv('XDG_CONFIG_HOME');
+                    if (!$xdgConfig) {
+                        $xdgConfig = $userDir . '/.config';
+                    }
+                    $home = $xdgConfig . '/composer';
+                } else {
+                    $home = $userDir . '/composer';
+                }
             }
         }
 
@@ -80,24 +87,64 @@ class Factory
                 } else {
                     $cacheDir = $home . '/cache';
                 }
+                $cacheDir = strtr($cacheDir, '\\', '/');
             } elseif (getenv('XDG_CONFIG_DIRS')) {
-                $followXDG = true;
                 $xdgCache = getenv('XDG_CACHE_HOME');
                 if (!$xdgCache) {
-                    $xdgCache = $userDir . '/.cache';
+                    $xdgCache = $home . '/.cache';
                 }
                 $cacheDir = $xdgCache . '/composer';
 
 
             } else {
-                $cacheDir = $home . '/.cache';
+                $cacheDir = $home . '/cache';
             }
         }
-        
+
+        return $cacheDir;
+    }
+
+    /**
+     * @param string $home
+     *
+     * @return string
+     */
+    protected static function getDataDir($home)
+    {
+        if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
+            $dataDir = strtr($home, '\\', '/');
+        } elseif (getenv('XDG_CONFIG_DIRS')) {
+            $xdgData = getenv('XDG_DATA_HOME');
+            if (!$xdgData) {
+                if (!getenv('HOME')) {
+                    throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
+                }
+                $userDir = rtrim(getenv('HOME'), '/');
+                $xdgData = $userDir . '/.local/share';
+            }
+            $dataDir = $xdgData . '/composer';
+        } else {
+            $dataDir = $home;
+        }
+
+        return $dataDir;
+    }
+
+    /**
+     * @param IOInterface|null $io
+     * @return Config
+     */
+    public static function createConfig(IOInterface $io = null)
+    {
+        // determine home and cache dirs
+        $home     = self::getHomeDir();
+        $cacheDir = self::getCacheDir($home);
+        $dataDir  = self::getDataDir($home);
+
         // Protect directory against web access. Since HOME could be
         // the www-data's user home and be web-accessible it is a
         // potential security risk
-        foreach (array($home, $cacheDir) as $dir) {
+        foreach (array($home, $cacheDir, $dataDir) as $dir) {
             if (!file_exists($dir . '/.htaccess')) {
                 if (!is_dir($dir)) {
                     @mkdir($dir, 0777, true);
@@ -107,22 +154,34 @@ class Factory
         }
 
         // Move content of old composer dir to XDG
-        if ($followXDG && file_exists($userDir . '/.composer')) {
-            // migrate to XDG
-            @rename($userDir . '/.composer/config.json', $home . '/config.json');
-            @unlink($userDir . '/.composer/.htaccess');
-            @unlink($userDir . '/.composer/cache/.htaccess');
-            foreach (glob($userDir . '/.composer/cache/*') as $oldCacheDir) {
-                @rename($oldCacheDir, $cacheDir . '/' . basename($oldCacheDir));
+        if (getenv('XDG_CONFIG_DIRS') !== false && getenv('COMPOSER_HOME') === false && getenv('COMPOSER_CACHE_DIR') === false) {
+            $userDir         = rtrim(getenv('HOME'), '/');
+            $oldComposerHome = $userDir . '/.composer';
+            if (file_exists($oldComposerHome)) {
+                // migrate to XDG
+                foreach (glob($oldComposerHome . '/*.json') as $file) {
+                    rename($file, $home . '/' . basename($file));
+                }
+
+                foreach (glob($oldComposerHome . '/*.phar') as $file) {
+                    rename($file, $dataDir . '/' . basename($file));
+                }
+
+                foreach (glob($oldComposerHome . '/cache/*') as $oldCacheDir) {
+                    rename($oldCacheDir, $cacheDir . '/' . basename($oldCacheDir));
+                }
+
+                unlink($oldComposerHome . '/.htaccess');
+                unlink($oldComposerHome . '/cache/.htaccess');
+                rmdir($oldComposerHome . '/cache');
+                rmdir($oldComposerHome);
             }
-            @rmdir($userDir . '/.composer/cache');
-            @rmdir($userDir . '/.composer');
         }
 
         $config = new Config();
 
         // add dirs to the config
-        $config->merge(array('config' => array('home' => $home, 'cache-dir' => $cacheDir)));
+        $config->merge(array('config' => array('home' => $home, 'cache-dir' => $cacheDir, 'data-dir' => $dataDir)));
 
         // load global config
         $file = new JsonFile($home.'/config.json');
@@ -149,14 +208,14 @@ class Factory
 
     public static function getComposerFile()
     {
-        return trim(getenv('COMPOSER')) ?: './composer.json';
+        return trim(getenv('COMPOSER')) ? : './composer.json';
     }
 
     public static function createAdditionalStyles()
     {
         return array(
             'highlight' => new OutputFormatterStyle('red'),
-            'warning' => new OutputFormatterStyle('black', 'yellow'),
+            'warning'   => new OutputFormatterStyle('black', 'yellow'),
         );
     }
 
@@ -172,15 +231,15 @@ class Factory
                 throw new \InvalidArgumentException('This function requires either an IOInterface or a RepositoryManager');
             }
             $factory = new static;
-            $rm = $factory->createRepositoryManager($io, $config);
+            $rm      = $factory->createRepositoryManager($io, $config);
         }
 
         foreach ($config->getRepositories() as $index => $repo) {
             if (!is_array($repo)) {
-                throw new \UnexpectedValueException('Repository '.$index.' ('.json_encode($repo).') should be an array, '.gettype($repo).' given');
+                throw new \UnexpectedValueException('Repository ' . $index . ' (' . json_encode($repo) . ') should be an array, ' . gettype($repo) . ' given');
             }
             if (!isset($repo['type'])) {
-                throw new \UnexpectedValueException('Repository '.$index.' ('.json_encode($repo).') must have a type defined');
+                throw new \UnexpectedValueException('Repository ' . $index . ' (' . json_encode($repo) . ') must have a type defined');
             }
             $name = is_int($index) && isset($repo['url']) ? preg_replace('{^https?://}i', '', $repo['url']) : $index;
             while (isset($repos[$name])) {
@@ -212,16 +271,16 @@ class Factory
 
         if (is_string($localConfig)) {
             $composerFile = $localConfig;
-            $file = new JsonFile($localConfig, new RemoteFilesystem($io));
+            $file         = new JsonFile($localConfig, new RemoteFilesystem($io));
 
             if (!$file->exists()) {
                 if ($localConfig === './composer.json' || $localConfig === 'composer.json') {
-                    $message = 'Composer could not find a composer.json file in '.getcwd();
+                    $message = 'Composer could not find a composer.json file in ' . getcwd();
                 } else {
-                    $message = 'Composer could not find the config file: '.$localConfig;
+                    $message = 'Composer could not find the config file: ' . $localConfig;
                 }
                 $instructions = 'To initialize a project, please create a composer.json file as described in the http://getcomposer.org/ "Getting Started" section';
-                throw new \InvalidArgumentException($message.PHP_EOL.$instructions);
+                throw new \InvalidArgumentException($message . PHP_EOL . $instructions);
             }
 
             $file->validateSchema(JsonFile::LAX_SCHEMA);
@@ -249,7 +308,7 @@ class Factory
         $io->loadConfiguration($config);
 
         $vendorDir = $config->get('vendor-dir');
-        $binDir = $config->get('bin-dir');
+        $binDir    = $config->get('bin-dir');
 
         // setup process timeout
         ProcessExecutor::setTimeout((int) $config->get('process-timeout'));
@@ -268,7 +327,7 @@ class Factory
         $this->addLocalRepository($rm, $vendorDir);
 
         // load package
-        $parser = new VersionParser;
+        $parser  = new VersionParser;
         $loader  = new Package\Loader\RootPackageLoader($rm, $config, $parser, new ProcessExecutor($io));
         $package = $loader->load($localConfig);
 
@@ -294,7 +353,7 @@ class Factory
         $this->createDefaultInstallers($im, $composer, $io);
 
         $globalRepository = $this->createGlobalRepository($config, $vendorDir);
-        $pm = $this->createPluginManager($composer, $io, $globalRepository);
+        $pm               = $this->createPluginManager($composer, $io, $globalRepository);
         $composer->setPluginManager($pm);
 
         if (!$disablePlugins) {
@@ -306,10 +365,8 @@ class Factory
 
         // init locker if possible
         if (isset($composerFile)) {
-            $lockFile = "json" === pathinfo($composerFile, PATHINFO_EXTENSION)
-                ? substr($composerFile, 0, -4).'lock'
-                : $composerFile . '.lock';
-            $locker = new Package\Locker($io, new JsonFile($lockFile, new RemoteFilesystem($io, $config)), $rm, $im, md5_file($composerFile));
+            $lockFile = "json" === pathinfo($composerFile, PATHINFO_EXTENSION) ? substr($composerFile, 0, -4) . 'lock' : $composerFile . '.lock';
+            $locker   = new Package\Locker($io, new JsonFile($lockFile, new RemoteFilesystem($io, $config)), $rm, $im, md5_file($composerFile));
             $composer->setLocker($locker);
         }
 
@@ -344,12 +401,12 @@ class Factory
      */
     protected function addLocalRepository(RepositoryManager $rm, $vendorDir)
     {
-        $rm->setLocalRepository(new Repository\InstalledFilesystemRepository(new JsonFile($vendorDir.'/composer/installed.json')));
+        $rm->setLocalRepository(new Repository\InstalledFilesystemRepository(new JsonFile($vendorDir . '/composer/installed.json')));
     }
 
-     /**
-     * @param  Config                                        $config
-     * @param  string                                        $vendorDir
+    /**
+     * @param Config $config
+     * @param string $vendorDir
      * @return Repository\InstalledFilesystemRepository|null
      */
     protected function createGlobalRepository(Config $config, $vendorDir)
@@ -358,7 +415,7 @@ class Factory
             return null;
         }
 
-        $path = $config->get('home').'/vendor/composer/installed.json';
+        $path = $config->get('home') . '/vendor/composer/installed.json';
         if (!file_exists($path)) {
             return null;
         }
@@ -486,4 +543,5 @@ class Factory
 
         return $factory->createComposer($io, $config, $disablePlugins);
     }
+
 }

From d3e6a464d6afe841c7e9387c94a2ed1596032cc4 Mon Sep 17 00:00:00 2001
From: Nicolas Toniazzi <nicolas@toniazzi.net>
Date: Mon, 15 Dec 2014 14:21:03 +0100
Subject: [PATCH 7/9] Fix home directory when system does not support XDG

---
 src/Composer/Factory.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index ad37cb594..20b1deee4 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -64,7 +64,7 @@ class Factory
                     }
                     $home = $xdgConfig . '/composer';
                 } else {
-                    $home = $userDir . '/composer';
+                    $home = $userDir . '/.composer';
                 }
             }
         }

From 1a5b87442ab784775a247b088a3f70123c1cd557 Mon Sep 17 00:00:00 2001
From: Nicolas Toniazzi <nicolas@toniazzi.net>
Date: Mon, 15 Dec 2014 15:10:15 +0100
Subject: [PATCH 8/9] Fix directory paths when using XDG

---
 src/Composer/Factory.php | 44 +++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index 20b1deee4..54e8ee589 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -37,6 +37,20 @@ use Composer\Package\Version\VersionParser;
 class Factory
 {
 
+    /**
+     * @return string
+     * @throws \RuntimeException
+     */
+    private static function getUserDir()
+    {
+        if (!getenv('HOME')) {
+            throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
+        }
+        $userDir = rtrim(getenv('HOME'), '/');
+
+        return $userDir;
+    }
+
     /**
      * @return string
      * @throws \RuntimeException
@@ -51,10 +65,7 @@ class Factory
                 }
                 $home = strtr(getenv('APPDATA'), '\\', '/') . '/Composer';
             } else {
-                if (!getenv('HOME')) {
-                    throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
-                }
-                $userDir = rtrim(getenv('HOME'), '/');
+                $userDir = self::getUserDir();
 
                 if (getenv('XDG_CONFIG_DIRS')) {
                     // XDG Base Directory Specifications
@@ -88,14 +99,18 @@ class Factory
                     $cacheDir = $home . '/cache';
                 }
                 $cacheDir = strtr($cacheDir, '\\', '/');
-            } elseif (getenv('XDG_CONFIG_DIRS')) {
-                $xdgCache = getenv('XDG_CACHE_HOME');
-                if (!$xdgCache) {
-                    $xdgCache = $home . '/.cache';
-                }
-                $cacheDir = $xdgCache . '/composer';
             } else {
-                $cacheDir = $home . '/cache';
+                $userDir = self::getUserDir();
+
+                if (getenv('XDG_CONFIG_DIRS')) {
+                    $xdgCache = getenv('XDG_CACHE_HOME');
+                    if (!$xdgCache) {
+                        $xdgCache = $userDir . '/.cache';
+                    }
+                    $cacheDir = $xdgCache . '/composer';
+                } else {
+                    $cacheDir = $home . '/cache';
+                }
             }
         }
 
@@ -114,10 +129,7 @@ class Factory
         } elseif (getenv('XDG_CONFIG_DIRS')) {
             $xdgData = getenv('XDG_DATA_HOME');
             if (!$xdgData) {
-                if (!getenv('HOME')) {
-                    throw new \RuntimeException('The HOME or COMPOSER_HOME environment variable must be set for composer to run correctly');
-                }
-                $userDir = rtrim(getenv('HOME'), '/');
+                $userDir = self::getUserDir();
                 $xdgData = $userDir . '/.local/share';
             }
             $dataDir = $xdgData . '/composer';
@@ -490,7 +502,7 @@ class Factory
      */
     protected function createPluginManager(Composer $composer, IOInterface $io, RepositoryInterface $globalRepository = null)
     {
-        return new Plugin\PluginManager($composer, $io, $globalRepository);
+        return new Plugin\PluginManager($io, $composer, $globalRepository);
     }
 
     /**

From e8a6cb536bf202b8e36937218117f36d5fffaad3 Mon Sep 17 00:00:00 2001
From: Nicolas Toniazzi <nicolas.toniazzi@altays.com>
Date: Wed, 22 Jul 2015 10:38:12 +0200
Subject: [PATCH 9/9] Change detection of config/cache/data dirs

---
 src/Composer/Factory.php | 166 +++++++++++++++++++++++----------------
 1 file changed, 97 insertions(+), 69 deletions(-)

diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index 2496692ed..19261739f 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -35,6 +35,21 @@ use Composer\Package\Version\VersionParser;
  */
 class Factory
 {
+    /**
+     *
+     * @return boolean
+     */
+    private static function useXdg()
+    {
+        foreach (array_keys($_SERVER) as $key) {
+            if (substr($key, 0, 4) === 'XDG_') {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * @return string
      * @throws \RuntimeException
@@ -56,28 +71,40 @@ class Factory
     protected static function getHomeDir()
     {
         $home = getenv('COMPOSER_HOME');
-        if (!$home) {
-            if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
-                if (!getenv('APPDATA')) {
-                    throw new \RuntimeException('The APPDATA or COMPOSER_HOME environment variable must be set for composer to run correctly');
-                }
-                $home = strtr(getenv('APPDATA'), '\\', '/') . '/Composer';
-            } else {
-                $userDir = self::getUserDir();
-
-                if (getenv('XDG_CONFIG_DIRS')) {
-                    // XDG Base Directory Specifications
-                    $xdgConfig = getenv('XDG_CONFIG_HOME');
-                    if (!$xdgConfig) {
-                        $xdgConfig = $userDir . '/.config';
-                    }
-                        $home = $xdgConfig . '/composer';
-                    } else {
-                        $home = $userDir . '/.composer';
-                }
-            }
+        if ($home) {
+            return $home;
         }
 
+        if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
+            if (!getenv('APPDATA')) {
+                throw new \RuntimeException('The APPDATA or COMPOSER_HOME environment variable must be set for composer to run correctly');
+            }
+            $home = strtr(getenv('APPDATA'), '\\', '/') . '/Composer';
+
+            return $home;
+        }
+
+        $userDir = self::getUserDir();
+
+        if (is_dir($userDir . '/.composer')) {
+            $home = $userDir . '/.composer';
+
+            return $home;
+        }
+
+        if (self::useXdg()) {
+            // XDG Base Directory Specifications
+            $xdgConfig = getenv('XDG_CONFIG_HOME');
+            if (!$xdgConfig) {
+                $xdgConfig = $userDir . '/.config';
+            }
+            $home = $xdgConfig . '/composer';
+
+            return $home;
+        }
+
+        $home = $userDir . '/.composer';
+
         return $home;
     }
 
@@ -89,29 +116,41 @@ class Factory
     protected static function getCacheDir($home)
     {
         $cacheDir = getenv('COMPOSER_CACHE_DIR');
-        if (!$cacheDir) {
-            if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
-                if ($cacheDir = getenv('LOCALAPPDATA')) {
-                    $cacheDir .= '/Composer';
-                } else {
-                    $cacheDir = $home . '/cache';
-                }
-                $cacheDir = strtr($cacheDir, '\\', '/');
-            } else {
-                $userDir = self::getUserDir();
-
-                if (getenv('XDG_CONFIG_DIRS')) {
-                    $xdgCache = getenv('XDG_CACHE_HOME');
-                    if (!$xdgCache) {
-                        $xdgCache = $userDir . '/.cache';
-                    }
-                    $cacheDir = $xdgCache . '/composer';
-                } else {
-                    $cacheDir = $home . '/cache';
-                }
-            }
+        if ($cacheDir) {
+            return $cacheDir;
         }
 
+        if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
+            if ($cacheDir = getenv('LOCALAPPDATA')) {
+                $cacheDir .= '/Composer';
+            } else {
+                $cacheDir = $home . '/cache';
+            }
+            $cacheDir = strtr($cacheDir, '\\', '/');
+
+            return $cacheDir;
+        }
+
+        $userDir = self::getUserDir();
+
+        if ($home === $userDir . '/.composer' && is_dir($home . '/cache')) {
+            $cacheDir = $home . '/cache';
+
+            return $cacheDir;
+        }
+
+        if (self::useXdg()) {
+            $xdgCache = getenv('XDG_CACHE_HOME');
+            if (!$xdgCache) {
+                $xdgCache = $userDir . '/.cache';
+            }
+            $cacheDir = $xdgCache . '/composer';
+
+            return $cacheDir;
+        }
+
+        $cacheDir = $home . '/cache';
+
         return $cacheDir;
     }
 
@@ -124,17 +163,31 @@ class Factory
     {
         if (defined('PHP_WINDOWS_VERSION_MAJOR')) {
             $dataDir = strtr($home, '\\', '/');
-        } elseif (getenv('XDG_CONFIG_DIRS')) {
+
+            return $dataDir;
+        }
+
+        $userDir = self::getUserDir();
+
+        if ($home === $userDir . '/.composer') {
+            $cacheDir = $home;
+
+            return $cacheDir;
+        }
+
+        if (self::useXdg()) {
             $xdgData = getenv('XDG_DATA_HOME');
             if (!$xdgData) {
                 $userDir = self::getUserDir();
                 $xdgData = $userDir . '/.local/share';
             }
             $dataDir = $xdgData . '/composer';
-        } else {
-            $dataDir = $home;
+
+            return $dataDir;
         }
 
+        $dataDir = $home;
+
         return $dataDir;
     }
 
@@ -163,31 +216,6 @@ class Factory
             }
         }
 
-        // Move content of old composer dir to XDG
-        if (getenv('XDG_CONFIG_DIRS') !== false && getenv('COMPOSER_HOME') === false && getenv('COMPOSER_CACHE_DIR') === false) {
-            $userDir         = rtrim(getenv('HOME'), '/');
-            $oldComposerHome = $userDir . '/.composer';
-            if (file_exists($oldComposerHome)) {
-                // migrate to XDG
-                foreach (glob($oldComposerHome . '/*.json') as $file) {
-                    rename($file, $home . '/' . basename($file));
-                }
-
-                foreach (glob($oldComposerHome . '/*.phar') as $file) {
-                    rename($file, $dataDir . '/' . basename($file));
-                }
-
-                foreach (glob($oldComposerHome . '/cache/*') as $oldCacheDir) {
-                    rename($oldCacheDir, $cacheDir . '/' . basename($oldCacheDir));
-                }
-
-                unlink($oldComposerHome . '/.htaccess');
-                unlink($oldComposerHome . '/cache/.htaccess');
-                rmdir($oldComposerHome . '/cache');
-                rmdir($oldComposerHome);
-            }
-        }
-
         $config = new Config(true, $cwd);
 
         // add dirs to the config